1. Field of the Invention
This invention relates to a reproduction system for maintaining the security of confidential documents and their reproductions.
2. Description of the Prior Art
In many fields, there is a need for huge quantities of information to be quickly exchanged between numbers of people. For this purpose, copying machines for copying documents, such as electrophotographic copying apparatus, and information transmission and recording apparatus, such as facsimile apparatus, have been developed and are widely used. At present, there are substantially no difficulties in making copies from ordinary documents. On the other hand, the development of copying apparatus and facsimile apparatus has brought about a new problem that confidential documents, for instance, new product planning documents, market research documents, diplomatic confidential materials or military confidential materials, are secretly copied without difficulty and those copies are stolen.
Under such circumstances, several methods of preventing reproduction of confidential documents by conventional electrophotographic copying machines have been proposed.
In this regard, a reproduction security system has been proposed wherein an "invisible" bar code is provided on the confidential document and the ability to copy same is controlled through the use of an encoded ID card containing a scrambled personal identification number in machine readable form and key pad for allowing the operator to input the personal identification number. The system is adapted to "read" the security code on the document, compare the card and key pad inputs to confirm the identity of the operator and to make encoded "blank" sheets of paper only if the operator's security clearance matches that indicated on the document. The use of encoded blank sheets prevents unauthorized reproductions made from copies of the original confidential document if copied on a similarly controlled copier. All of this is done on a separate dedicated xerographic printer machine that is not itself an image duplicator. Using this machine a fluorescent invisible data encoding is provided to blank sheets of paper for use in subsequent typing, printing or xerographic copying of confidential documents. When reproduction of confidential documents is to be done, encoded "blank" paper is obtained from this machine and the paper used promptly in a xerographic copier to reproduce the original document. The copier is provided with means to compare the encoding on the blank sheets with that on the original before copies of same can be made. The machine logic may be similar to that of the printer in requiring the operator to prove his/her identity. In addition, the copy sheets may be provided with time of encoding to ensure that the "blank" copy paper is used promptly; i.e., the copier can be made to shut down when "stale" encoded copy paper is used for making copies of secure documents.
It is one object of the invention to improve upon the security systems of the prior art. For example, in the recited prior art system documents encoded with different security levels may be required to be copied in the same order of their respective encoded blank copy paper. Care would thus need to be exercised to maintain the order of copying with the order in which the "blank" encoded paper was produced. Any mixing would prove a problem since the encoding on the blank sheets are not visible. Furthermore, extra time and space is wasted in having to move from printer to copy machine.